We have collected over 200 nuclear families (mother, father and Child) with undiagnosed multiple congenital anomaly syndrome. Our approach is to use molecular techniques to detect submicroscopic duplications and deletions. The analysis of the specimens is incomplete although we have already found a number of abnormalities.By screening with microsatellite markers, we have found five chromosomal aberrations that were not detected by microscopic techniques. The study will be closed to further accrual this year to allow completion of the analysis of the current specimens.